THURSDAY, Nov. 14 (HealthDay News) -- Teens who stay up late are more likely to have lower grades and more emotional problems, a new study suggests.

Researchers analyzed data from 2,700 U.S. teens, aged 13 to 18. Of those, 30 percent said they went to bed later than 11.30 p.m. on school nights and 1:30 a.m. in the summer.

By the time they graduated from high school, the teens who stayed up late during the school year had lower GPA scores and were more likely to have emotional problems than those with earlier bedtimes, the University of California, Berkeley, team found.

Going to bed late in the summer did not appear to affect school performance, but there was an association between later summer bedtimes and emotional problems in young adulthood, according to the study published online Nov. 10 in the Journal of Adolescent Health.

The researchers said their findings support later middle and high school morning start times. While the study found an association between lack of sleep and lower grades, it did not prove a cause-and-effect relationship.

"Academic pressures, busy after-school schedules and the desire to finally have free time at the end of the day to connect with friends on the phone or online make this problem even more challenging," study author Lauren Asarnow, a graduate student in UC Berkeley's sleep and mood research clinic, said in a university news release.

On a positive note, the findings highlight how healthy sleep habits provide academic and emotional benefits for teens.

"The good news is that sleep behavior is highly modifiable with the right support," Asarnow said.